class_docstr: Megatron BART pretraining
docstr: Class-specific cfg validation
docstr_tok: ["Class-specific","cfg","validation"]
code: def _validate_cfg(self):
      """Class-specific cfg validation"""
      if self._cfg.data.get("dataset_type", None) != "bart":
          raise ValueError(
              f"cfg.data.dataset_type = {self._cfg.data.get('dataset_type', None)} but 'bart' is expected"
          )
  
      if self.num_sentinel_tokens != 0:
          raise ValueError(
              f"cfg.tokenizer.num_sentinel_tokens = {self.num_sentinel_tokens} but 0 is expected for 'bart'"
          )
  
file_path: NeMo/nemo/collections/nlp/models/language_modeling/megatron_bart_model.py
imports: from omegaconf.dictconfig import DictConfig
  from pytorch_lightning.trainer.trainer import Trainer
  from nemo.collections.nlp.models.language_modeling.megatron_t5_model import MegatronT5Model
label_desc: Use image node_id 3 for calling the MegatronBARTModel obj's underlying member method code with example usage: obj._validate_cfg() without return types